Serial hemodynamic studies and simultaneous radionuclide angiograph were performed in patients with septic shock. Survivors most commonly developed a profound but reversible depression of the left ventricular ejection fraction and dilatation of the ventricle. These changes returned to normal about one week after the onset of shock. Nonsurvivors had a variable change in ejection fraction (EF) but as a group had only a mild decrease in ejection fraction with no significant difference in EF from critically ill, nonseptic control patients. The nonsurvivors, however, did not develop left ventricular dilatation when the EF was depressed. This inability to dilate the left ventricle may have produced an inadequate stroke volume, thus contributing to the patient's demise. Cardiovascular abnormalities induced by sepsis are the most common cause of death in ICU patients. Understanding the cardiovascular changes should allow better treatment of septic shock patients.